This invention relates to to dynamoelectric machines having unbalanced rotor assemblies and, more particularly, to a method and apparatus of constructing such a rotor assembly in a better and more economical manner than heretofore possible.
In certain electric motor applications, especially those in which air is pumped through a system to entrain an object in the airstream and move it from one place to another, damaging motor vibrations are often produced. One way of counteracting these vibrations is by applying counterweights to the the rotor assembly portion of the motor. Properly sized counterweights properly positioned will reduce, or eliminate the vibration problem. As a tradeoff, however, there is an increase in the manufactured cost of the motor. This is so, not only because of the added material in the motor, but also because of the time and labor required to attach counterweights to the assembly. Inclusion of counterweights in the motor of course means additional steps in the manufacturing process. Since precision of placement of the counterweights is vital in eliminating the vibration problem, care must be taken to insure the placement is correct. It will be appreciated that if counterweights are not correctly located, they may actually exacerbate the vibration problem, not solve it. What would be useful would be a way of readily incorporating the placement of counterweights as part of the rotor assembly, since this would help minimize any increased manufacturing costs. At the same time, if the accuracy of weight placement were insured, the effectiveness of the included weights could be assured, thus prolonging the useful life of the motor in these applications. In this latter regard, it would also be helpful if the resultant rotor assembly were an unbalanced assembly. This is important because an unbalanced assembly is more effective in eliminating the effects of vibrations in the above referenced motor applications.